MPD: util/Manual.hxx Source File

MPD 0.20.15

Manual.hxx
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1 /*
2 * Copyright (C) 2013 Max Kellermann <max.kellermann@gmail.com>
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 *
8 * - Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 *
11 * - Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the
14 * distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
19 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
20 * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
22 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
23 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
25 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
26 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
27 * OF THE POSSIBILITY OF SUCH DAMAGE.
28 */
29
30 #ifndef MPD_MANUAL_HXX
31 #define MPD_MANUAL_HXX
32
33 #include "Compiler.h"
34
35 #include <new>
36 #include <utility>
37
38 #include <assert.h>
39
40 #if CLANG_OR_GCC_VERSION(4,7)
41 #pragma GCC diagnostic push
42 #pragma GCC diagnostic ignored "-Wstrict-aliasing"
43 #endif
44
51 template<class T>
52 class Manual {
53 alignas(T)
54 char data[sizeof(T)];
55
56 #ifndef NDEBUG
57 bool initialized;
58 #endif
59
60 public:
61 #ifndef NDEBUG
62 Manual():initialized(false) {}
63 ~Manual() {
64 assert(!initialized);
65 }
66 #endif
67
68 template<typename... Args>
69 void Construct(Args&&... args) {
70 assert(!initialized);
71
72 void *p = data;
73 new(p) T(std::forward<Args>(args)...);
74
75 #ifndef NDEBUG
76 initialized = true;
77 #endif
78 }
79
80 void Destruct() {
81 assert(initialized);
82
83 T &t = Get();
84 t.T::~T();
85
86 #ifndef NDEBUG
87 initialized = false;
88 #endif
89 }
90
91 T &Get() {
92 assert(initialized);
93
94 void *p = static_cast<void *>(data);
95 return *static_cast<T *>(p);
96 }
97
98 const T &Get() const {
99 assert(initialized);
100
101 const void *p = static_cast<const void *>(data);
102 return *static_cast<const T *>(p);
103 }
104
105 operator T &() {
106 return Get();
107 }
108
109 operator const T &() const {
110 return Get();
111 }
112
113 T *operator->() {
114 return &Get();
115 }
116
117 const T *operator->() const {
118 return &Get();
119 }
120 };
121
122 #if CLANG_OR_GCC_VERSION(4,7)
123 #pragma GCC diagnostic pop
124 #endif
125
126 #endif
Manual::Manual
Manual()
Definition: Manual.hxx:62
Manual::operator->
T * operator->()
Definition: Manual.hxx:113
Manual::Get
T & Get()
Definition: Manual.hxx:91
Manual::operator->
const T * operator->() const
Definition: Manual.hxx:117
Manual
Container for an object that gets constructed and destructed manually.
Definition: Manual.hxx:52
Manual::Destruct
void Destruct()
Definition: Manual.hxx:80
Compiler.h
Manual::Construct
void Construct(Args &&... args)
Definition: Manual.hxx:69
Manual::Get
const T & Get() const
Definition: Manual.hxx:98
Manual::~Manual
~Manual()
Definition: Manual.hxx:63